GABA is a neurotransmitter involved in normal regulation of the mammalian central nervous system. An imbalance in GABA concentrations in the central nervous system has been implicated in several disease states, including; seizures, Huntington's chorea, Parkinson's disease, spasticity, and neuropathic pain. Treatment of these disease states has generally centered on increasing GABA concentrations in the afflicted patient's central nervous system. Purpura et al., Neurochem, 1959;3:238-268; Spokes., Adv. Exp. Med. Biol., 1978:123:461-473; Wu et al., Neurochem. Res., 1979;14:575-586. Unfortunately, direct treatment of afflicted patients with GABA has proven ineffective as GABA has physiochemical properties that prohibit it from crossing the blood-brain barrier.
Structurally related compounds to GABA are being pursued as possible treatments for GABA mediated disorders. Gabapentin (1-(aminomethyl) cyclohexaneacetic acid) is one such structurally related compound which is known to readily cross the blood-brain barrier and bind throughout the central nervous system. Gabapentin is currently used in the treatment of seizures and epilepsy and has been implicated as a possible treatment in other GABA mediated central nervous system disorders.
There is a need in the relevant art to have additional compounds that have gabapentin like activity. Other gabapentin related drugs may be more effective than gabapentin in treating seizures and other central nervous system disorders, or may be used in patients that have become refractory to gabapentin over time or have unwanted side effects. Against this backdrop the present invention has been developed.